Patent GB-1041469-A (GB)
Title: Process for the continuous, simultaneous separation of the normal aliphatic and aromatic components of hydrocarbon mixtures
IPC: C07C9/14
Filed: 1963-06-07
Abstract: A continuous process for simultaneously separating aromatic and normal aliphatic hydrocarbons from mixtures also containing branched chain and/or naphthenic hydrocarbons comprises introducing said mixture into the sorption zone of an elongated fixed bed of solid particles comprising mixed selective sorbents for aromatic and normal aliphatic hydrocarbons and also having a primary rectification zone, a first desorption zone, a secondary rectification zone, a second desorption zone and a tertiary rectification zone, passing said mixture through said sorption zone and during said passage effecting sorption of aromatic and normal aliphatic hydrocarbons by said mixed sorbents, withdrawing from the sorbent bed at the outlet of the sorption zone a portion of resulting stream comprising raphinate hydrocarbon and passing the remaining portion thereof into the adjacent downstream tertiary rectification zone of said sorbent bed, passing the resulting stream issuing from the outlet of the tertiary rectification zone into the first desorption zone, also introducing into the passing through said first desorption zone, a desorbent stream which desorbs one of the sorbed components, withdrawing from the sorbent bed at the outlet of the first desorption zone a portion of the resulting stream comprising desorbate and passing the remaining portion thereof into the adjacent downstream secondary rectification zone of said sorbent bed, passing the resulting stream issuing from the outlet of the secondary rectification zone into the adjacent downstream second desorption zone, also introducing into the second desorption zone, a desorbent stream which desorbs the other of the sorbed components, withdrawing from the sorbent bed at the outlet of the second desorption zone a portion of the resulting stream comprising desorbate and passing the remaining portion thereof into the adjacent downstream primary rectification zone of said sorbent bed, introducing the resulting stream issuing from the outlet of the primary rectification zone into the sorption zone with the feed mixture, and periodically advancing in equal increments downstream the points of introduction of feed mixture and desorbents and the points of withdrawal of raffinate and desorbate streams, and thereby advancing simultaneously the corresponding sorption, desorption and rectification zones defined by said points of introduction and points of withdrawal. The desorbent is preferably a lower molecular weight more volatile hydrocarbon of the same type as the respective aromatic and normal aliphatic hydrocarbons to be desorbed.  The selective sorbent for the normal aliphatic hydrocarbons may be a 4-6<\>rA dehydrated metal aluminosilicate, and for the aromatics a 6-10<\>rA dehydrated metal aluminosilicate, activated charcoal, or silica gel.ALSO:A continuous process for simultaneously separating aromatic and normal aliphatic hydrocarbons from mixtures also containing branched chain and/or naphthenic hydrocarbons comprises introducing said mixture into the adsorption zone of an elongated fixed bed of solid particles comprising mixed selective sorbents for aromatic and normal aliphatic hydrocarbons and also having a primary rectification zone, a first desorption zone, a secondary rectification zone, a second desorption zone and a tertiary rectification zone, passing said mixture through said sorption zone and during said passage effecting sorption of aromatic and normal aliphatic hydrocarbons by said mixed sorbents, withdrawing from the sorbent bed at the outlet of the sorption zone a portion of resulting stream comprising raffinate hydrocarbon and passing the remaining portion thereof into the adjacent downstream tertiary rectification zone of said sorbent bed, passing the resulting streams issuing from the outlet of the tertiary rectification zone into the first desorption zone, also introducing into and passing through said first desorption zone, a desorbent stream which desorbs one of the sorbed components, withdrawing from the sorbent bed at the outlet of the first desorption zone a portion of the resulting stream comprising desorbate and passing the remaining portion thereof into the adjacent downstream secondary rectification zone of said sorbent bed, passing the resulting stream issuing from the outlet of the secondary rectification zone into the adjacent downstream second desorption zone, also introducing into the second desorption zone, a desorbent stream which desorbs the other of the sorbed components, withdrawing from the sorbent bed at the outlet of the second desorption zone a portion of the resulting stream comprising desorbate and passing the remaining portion thereof into the adjacent downstream primary rectification zone of said sorbent bed, introducing the resulting stream issuing from the outlet of the primary rectification zone into the sorption zone with the feed mixture, and periodically advancing in equal increments downstream the points of introduction of feed mixture and desorbents and the points of withdrawal of raffinate and desorbate streams, and thereby advancing simultaneously the corresponding sorption, desorption and rectification zones, defined by said points of introduction and points of withdrawal. The desorbent is preferably a lower molecular weight more volatile hydrocarbon of the same type as the respective aromatic and normal aliphatic hydrocarbons to be desorbed.  The selective sorbent for the normal aliphatic hydrocarbons may be a 4-6\rA dehydrated metal aluminosilicate, and for the aromatics a 6-10A dehydrated metal aluminosilicate, activated charcoal, or silica gel.